1. Field of the Invention
The present invention generally relates to an assembly for removing submicron to micron sized ferrous particles from moving liquids and in particular, is concerned with a magnetic assembly locatable on an oil filter canister usable within a closed system of lubricating oil with the magnetic assembly attracting and holding ferrous particles entrained within the oil preventing circulation of these particles within the closed system and thereby the engine to which the closed system connects.
2. Description of the Prior Art
Most engines used in automobiles, trucks and boats include canister-shaped oil filters that filter the engine's lubricating oil, removing foreign matter therefrom. To eliminate the larger particles of foreign matter, the engine oil is typically forced through a porous material in the oil filter that allows the liquid oil to pass through, but does not allow the passage of the larger particles. In this manner, the larger particles of foreign matter can be removed from the engine's lubricating oil. However, because this separation technique relies upon filtration through a porous material, particles that are smaller than the openings in the porous material are normally not removed by the filter medium. One particularly harmful type of foreign matter in lubricating oil is the small metallic (also ferrous) particles which are created by the frictional contact between the moving metal parts of the engine. These metallic particle contaminants can damage important engine components as such circulate through the engine.
Small metallic particles often have a cross-sectional dimension smaller than the openings in the porous filter material. When not removed by the oil filter, these small metallic particles will freely circulate through the engine until they are finally removed when the oil is changed. Typically, the porous material used in oil filters consists of a fibrous material that has openings with an average diameter greater than 20 microns. Hence, metallic particles with a cross-sectional dimension of 20 microns or smaller are often not trapped by the filter. Some metallic particles are larger than 20 microns. These metallic particles have sharp edges. Movement of these large particles by the force of the flow of the oil will cause these particles to "slice" like a knife through the filter producing holes greater than 20 microns thereby decreasing the filtering effectiveness of the oil filter.
The micron and submicron sized metallic particles are a major cause of wear of the moving components of the engine. Specifically, as the oil is circulated throughout the engine to lubricate the various moving components, the metallic particles entrained in the oil are carried to the interface between the moving components. At these locations, the hardness of the metallic particles causes metal to bear against metal, and reliance is placed solely upon the oil to maintain a lubricating film. When these metallic particles are brought to these interfaces, damage to the adjoining surfaces is likely. This damage eventually results in a degradation of the close tolerances between the moving parts, causing a loss in operating engine efficiency and more frequent maintenance in the form of repair. By some estimates, these metallic particles are the cause of more than one-half of the wear in the engine.
One approach taken by the prior art to eliminate these particles has been to install a magnetized drain plug in the crankcase of the engine. The magnetized drain plug generates a magnetic field around the magnet within the crankcase, which in turn attracts and removes some of the metallic particles from the lubricating oil as it flows through the crankcase. However, when the engine is running, the flow of oil through the crankcase can be at such a high flow rate so as to carry the metallic particles entirely through the magnetic field produced by the magnetized drain plug. In other cases, the magnetic field itself is insufficiently strong or extensive to attract and remove a meaningful number of particles from the lubricating oil.
Another prior approach to solve this problem has been to attach a magnet to the oil filter canister intending to create a magnetic field within the filter to attract and hold the ferrous particles against the walls of the filter. Unfortunately, these prior art attempts did not generate a sufficiently strong magnetic field to attract and hold any significant number of the metallic particles in the oil. The metallic particles contained in the oil, even if such pass through the magnetic field, are not likely to be attracted and held and thus continue to circulate through the engine.
A magnetic belt assembly for oil filters is disclosed in U.S. Pat. No. 3,460,679. This patent teaches securing the outside surface of permanent magnets to the inner surface of an annular spring steel belt. The belt is placed around an oil filter cartridge with the inner surfaces of the magnets engaging the outer surface of the cartridge. A magnetic field is supposed to be created by the magnets through the cartridge wall to attract metallic particles from the oil therein. The magnets are elongated and aligned axially on the cartridge. The magnets are spaced relative to each other on the spring steel belt which is more narrow than the elongated axial dimension of the magnets. As a result, only the middle region of the back surface of the magnets is covered by the narrow belt.
One significant problem associated with the device disclosed in U.S. Pat. No. 3,460,679 is the inability to generate a sufficiently strong magnetic field within the filter cartridge. The intensity of the magnetic field generated by the magnets is greater on the outside of the cartridge than on the inside thereof due to the influence of the ferrometallic cylindrical outer wall of the cartridge. The present inventor actually constructed a device according to U.S. Pat. No. 3,460,679 and used a gauss meter to measure the amount of magnetic force that was produced. The magnets that were used were bonded to iron having approximately a 5 MG maximum energy product. The band utilized was constructed of spring steel of a thickness of 0.032 of an inch with a width of 0.375 of an inch. There were ten magnets used that were located circumferentially around the filter canister about two inches from the top surface of the canister. The annular spring steel belt was centered over the middle of the magnets thus about 37.5% of the back of the magnets was covered by the annular spring steel belt. The magnets were separated from each other by 1.25 inch from edge to edge in a circumferential direction. The gauss readings on the back of the annular spring steel belt were 836 gauss, on the back of the exposed magnets was 1526 gauss, with the reading inside the canister being only 98 gauss. It can thus be seen that compared to the total magnet field strength of the magnets only about 7% of the total magnetic is field intensity supplied to within the canister. Therefore, most of the metallic particles suspended in the oil flowing within the cartridge are not retained within the cartridge by the relatively weak magnetic field therein.
Reference is to be had to U.S. Pat. No. 3,402,820, Lohmann, in which there Was disclosed a magnetic cleaner for a coolant. The coolant is to be moved through an elongated conduit and on the exterior wall of the conduit is mounted a magnetic arrangement. The magnetic arrangement comprises a plurality of different magnets which are separated by spacers. The magnets and the spacers are retained in place on the conduit by means of a clamping arrangement on the exterior surface of the magnetic arrangement. This structure of Lohmann was never designed to be utilized within a pressurized environment where the structure of the present invention is intended to be used. In most instances the mounting of an oil filter within an engine is in a very restricted area with very little space being left between the oil filter and the engine block or other associated parts of the engine. In other words, space is minimal. The structure of Lohmann is of such a great size that it would be incapable of being used in conjunction with an oil filter mounted on an engine. Additionally the spacing of the magnets within Lohmann substantially decreases the magnetic field within the elongated conduit. The present inventor constructed the device of Lohmann and again made gauss readings on the device. Magnets used were the same as those used in the discussion in the reference of U.S. Pat. No. 3,460,679. Because of the spacing of the magnets within Lohmann, the magnetic field recorded only 0.63 kG within the canister. If the magnets were placed in a flush abutting relationship as is the case within the present invention, the reading would increase within the canister to 1.69 kG.
Consequently, a need exists for an improved device for removing micron and submicron sized ferrometallic particles from the lubricating oil flowing through an engine. To this end, there is a need for an inexpensive device that can generate a stronger magnetic field than any of the devices known heretofore in the art. One embodiment of this device should be mountable on the outside of an oil filter and adaptable for use on different sizes of oil filters. This device should also be readily removable and reusable on different oil filters. Further, this device should be mounted on an oil filter in such a manner that minimizes the opportunity for the device to become detached from the oil filter.